Outboard Motor Question

[catsmeow]

Have a 1995 90hp Mariner Outboard. Had the water pump serviced last year. Tough year with work have not been able to get out. Have been starting it and running it in the driveway a few times. First that I notice a black oil leak on the floor after I put it back in the garage. Left the motor tilted up a little. Black oil is coming out if a small hole on lower unit below the cavitation plate at the back and a little above the prop. Is this just a normal exhaust thing or is it something I should be concerned about. Never seen this kind of leak before. Wanted to take the grand kids out for ride this coming Tuesday. Any thoughts appreciated. Thanks... Walt